How would one install a side by side installation of Python 2.x, and Python 3.x

Question

I think the title says it all.

Answer 1

Python 3 is available from the repositories and can be installed side by side with Python 2:

sudo apt-get install python3 python

You can use the -V switch to find out the minor version numbers:

$ python3 -V
Python 3.1.2

$ python -V
python 2.6.6